Image forming apparatus that detects image forming condition

Abstract

An image forming apparatus has an image forming unit for forming a toner image on a recording material, the image forming unit including an image bearing member for bearing a toner image, and a charging device provided with a magnetic particle layer contactable to the image bearing member to charge the image bearing member; and a determining device for determining an image forming condition of the image forming unit in accordance with a physical quantity relating to a toner amount introduced in the magnetic particle layer or deciding prohibition of the image forming operation of the image forming unit.

What is claimed is: 
     
       1. An image forming apparatus comprising: image forming means for forming a toner image on a recording material, said image forming means including an image bearing member for bearing a toner image, and charging means provided with a magnetic particle layer contactable to said image bearing member to charge said image bearing member; and   determining means for determining an image forming condition of said image forming means, wherein the determinations are made in accordance with a density of toner returned from said charging means to said image bearing member.   
     
     
       2. An apparatus according to claim 1, wherein the image forming condition is a charging condition of said charging means. 
     
     
       3. An apparatus according to claim 2, further comprising means for supplying said charging means with an oscillating voltage, and wherein said determining means changes a peak-to-peak voltage of the oscillating voltage in accordance with the density of toner. 
     
     
       4. An apparatus according to any one of claims 1, 2 or 3, wherein said image forming means includes developing means for developing with the toner a latent image formed on said image bearing member, and said developing means removes residual toner from the image bearing member simultaneously with its developing operation. 
     
     
       5. An apparatus according to any one of claims 1, 2 or 3, wherein said bearing member has a surface layer having a volume resistivity of 1×10 10  -1×10 14  Ωcm. 
     
     
       6. An apparatus according to claim 5, wherein said image bearing member has a photosensitive layer inside said surface layer. 
     
     
       7. An image forming apparatus comprising: image forming means for forming a toner image on a recording material, said image forming means including an image bearing member for bearing a toner image, and charging means provided with a magnetic particle layer contactable to said image bearing member to charge said image bearing member; and   determining means for determining a discharging condition of a discharging operation for discharging the toner to said image bearing member from said charging means in accordance with a density of toner returned from said charging means to said image bearing member.   
     
     
       8. An apparatus according to claim 7, wherein said determining means determines whether to execute the discharging operation. 
     
     
       9. An apparatus according to claim 7, wherein said determining means changes an operation period of the discharging operation. 
     
     
       10. An apparatus according to claim 7, wherein said determining means changes a potential difference between a potential of said image bearing member to be charged by said charging means and a DC voltage applied to said charging means, in accordance with the density of toner. 
     
     
       11. An apparatus according to claim 7, further comprising means for supplying said charging means with an oscillating voltage, and wherein said determining means changes a peak-to-peak voltage of the oscillating voltage is accordance with the density of toner. 
     
     
       12. An apparatus according to any one of claims 7, 8, 9, 10 or 11, wherein said image forming means includes developing means for developing with the toner a latent image formed on said image bearing member, and said developing means removes residual toner from the image bearing member simultaneously with its developing operation. 
     
     
       13. An apparatus according to any one of claims 7, 8, 9, 10 or 11, wherein said image bearing member has a surface layer having a volume resistivity of 1×10 10  -1×10 14  Ωcm. 
     
     
       14. An apparatus according to claim 13, wherein said image bearing member has a photosensitive layer inside said surface layer. 
     
     
       15. An image forming apparatus comprising: image forming means for forming a toner image on a recording material, said image forming means including an image bearing member for bearing a toner image, and charging means provided with a magnetic particle layer contactable to said image bearing member to charge said image bearing member; and   determining means for determining a charging condition of said charging means, wherein the determinations are made in accordance with current through said charging means when said charging means is supplied with a predetermined voltage.   
     
     
       16. An apparatus according to claim 15, wherein said determining means determines when an image forming operation of said image forming means is to be prohibited in accordance with the current. 
     
     
       17. An apparatus according to claim 16, further comprising means for supplying said charging means with an oscillating voltage, and wherein said determining means changes a peak-to-peak voltage of the oscillating voltage in accordance with the current through said charging means. 
     
     
       18. An apparatus according to any one of claims 15, 16 or 17, wherein said image forming means includes developing means for developing with the toner a latent image formed on said image bearing member, and said developing means removes residual toner from the image bearing member simultaneously with its developing operation. 
     
     
       19. An apparatus according to any one of claims 15, 16 or 17, wherein said image bearing member has a surface layer having a volume resistivity of 1×10 10  -1×10 14  Ωcm. 
     
     
       20. An apparatus according to claim 19, wherein said image bearing member has a photosensitive layer inside said surface layer. 
     
     
       21. An image forming apparatus comprising: image forming means for forming a toner image on a recording material, said image forming means including an image bearing member for bearing a toner image, and charging means provided with a magnetic particle layer contactable to said image bearing member to charge said image bearing member;   detecting means for optically detecting a toner amount in said magnetic particle layer; and   determining means for determining an image forming condition of said image forming means and for determining when an image forming operation of said image forming means is to be prohibited, wherein the determinations are made in accordance with toner amount detected by said detected means.   
     
     
       22. An apparatus according to claim 21, wherein the image forming condition is a charging condition of said charging means. 
     
     
       23. An apparatus according to claim 22, further comprising means for supplying said charging means with an oscillating voltage, and wherein said determining means changes a peak-to-peak voltage of the oscillating voltage in accordance with the toner amount detected by said detecting means. 
     
     
       24. An apparatus according to any one of claims 21, 22 or 23, wherein said image forming means includes developing means for developing with the toner a latent image formed on said image bearing member, and said developing means removes residual toner from the image bearing member simultaneously with its developing operation. 
     
     
       25. An apparatus according to any one of claims 21, 22 or 23, wherein said image bearing member has a surface layer having a volume resistivity of 1×10 10  -1×10 14  Ωcm. 
     
     
       26. An apparatus according to claim 25, wherein said image bearing member has a photosensitive layer inside said surface layer. 
     
     
       27. An image forming apparatus comprising: image forming means for forming a toner image on a recording material, said image forming means including an image bearing member for bearing a toner image, charging means provided with a magnetic particle layer contactable to said image bearing member to charge said image bearing member, and transferring means for transferring the toner image from said image bearing member onto the recording material; and   determining means for determining a discharging condition of a discharging operation for discharging toner to said image bearing member from said charging means in accordance with an amount of residual toner on said image bearing member after image transfer operation of said transferring means.   
     
     
       28. An apparatus according to claim 27, wherein said determining means changes a potential difference between a potential of said image bearing member to be charged by said charging means and a DC voltage applied to said charging means, in accordance with the amount of residual toner. 
     
     
       29. An apparatus according to claim 27, further comprising means for supplying said charging means with an oscillating voltage, and wherein said determining means changes a peak-to-peak voltage of the oscillating voltage is accordance with the amount of residual toner. 
     
     
       30. An apparatus according to any one of claims 27, or 28, wherein said image forming means includes developing means for developing with the toner a latent image formed on said image bearing member, and said developing means removes residual toner from the image bearing member simultaneously with its developing operation. 
     
     
       31. An apparatus according to any one of claims 27, 28 or 29, wherein said image bearing member has a surface layer having a volume resistivity of 1×10 10  -1×10 14  Ωcm. 
     
     
       32. An apparatus according to claim 31, wherein said image bearing member has a photosensitive layer inside said surface layer. 
     
     
       33. An image forming apparatus comprising: image forming means for forming a toner image on a recording material, said image forming means including an image bearing member for bearing a toner image, charging means provided with a magnetic particle layer contactable to said image bearing member to charge said image bearing member, and latent image forming means for forming a latent image on said image bearing member in accordance with image data; and   determining means for determining a discharging condition of a discharging operation for discharging the toner to said image bearing member from said charging means in accordance with the image data.   
     
     
       34. An apparatus according to claim 33, wherein said determining means changes a potential difference between a potential of said image bearing member to be charged by said charging means and a DC voltage applied to said charging means, in accordance with the image data. 
     
     
       35. An apparatus according to claim 33, further comprising means for supplying said charging means with an oscillating voltage, and wherein said determining means changes a peak-to-peak voltage of the oscillating voltage is accordance with the image data. 
     
     
       36. An apparatus according to any one of claims 33, 34 or 35, wherein said image forming means includes developing means for developing with the toner a latent image formed on said image bearing member, and said developing means removes residual toner from the image bearing member simultaneously with its developing operation. 
     
     
       37. An apparatus according to any one of claims 33, 34 or 35, wherein said image bearing member has a surface layer having a volume resistivity of 1×10 10  -1×10 14  Ωcm. 
     
     
       38. An apparatus according to claim 37, wherein said image bearing member has a photosensitive layer inside said surface layer. 
     
     
       39. An image forming apparatus comprising: image forming means for forming a toner image on a recording material, said image forming means including an image bearing member for bearing a toner image, charging means provided with a magnetic particle layer contactable to said image bearing member to charge said image bearing member; and   determining means for determining a discharging condition of discharging operation for discharging the toner to said image bearing member from said charging means in accordance with current through said charging means when said charging means is supplied with a predetermined voltage.   
     
     
       40. An apparatus according to claim 39, wherein said determining means changes a potential difference between a potential of said image bearing member to be charged by said charging means and a DC voltage applied to said charging means, in accordance with the current through said charging means. 
     
     
       41. An apparatus according to claim 39, further comprising means for supplying said charging means with an oscillating voltage, and wherein said determining means changes a peak-to-peak voltage of the oscillating voltage is accordance with the current through said charging means. 
     
     
       42. An apparatus according to any one of claims 39, 40 or 41, wherein said image forming means includes developing means for developing with the toner a latent image formed on said image bearing member, and said developing means removes residual toner from the image bearing member simultaneously with its developing operation. 
     
     
       43. An apparatus according to any one of claims 39, 40 or 41, wherein said image bearing member has a surface layer having a volume resistivity of 1×10 10  -1×10 14  Ωcm. 
     
     
       44. An apparatus according to claim 43, wherein said image bearing member has a photosensitive layer inside said surface layer. 
     
     
       45. An image forming apparatus comprising: image forming means for forming a toner image on a recording material, said image forming means including an image bearing member for bearing a toner image, and charging means provided with a magnetic particle layer contactable to said image bearing member to charge said image bearing member;   detecting means for optically detecting a toner amount in said magnetic particle layer; and   determining means for determining a discharging condition of a discharging operation for discharging the toner to said image bearing member from said charging means in accordance with the toner amount detected by said detecting means.   
     
     
       46. An apparatus according to claim 45, wherein said determining means changes a potential difference between a potential of said image bearing member to be charged by said charging means and a DC voltage applied to said charging means, in accordance with the toner amount detected by said detecting means. 
     
     
       47. An apparatus according to claim 45, further comprising means for supplying said charging means with an oscillating voltage, and wherein said determining means changes a peak-to-peak voltage of the oscillating voltage is accordance with the toner amount detected by said detecting means. 
     
     
       48. An apparatus according to any one of claims 45, 46 or 47, wherein said image forming means includes developing means for developing with the toner a latent image formed on said image bearing member, and said developing means removes residual toner from the image bearing member simultaneously with its developing operation. 
     
     
       49. An apparatus according to any one of claims 45, 46 or 47, wherein said image bearing member has a surface layer having a volume resistivity of 1×10 10  -1×10 14  Ωcm. 
     
     
       50. An apparatus according to claim 49, wherein said image bearing member has a photosensitive layer inside said surface layer. 
     
     
       51. An image forming apparatus comprising: image forming means for forming a toner image on a recording material, said image forming means including an image bearing member for bearing a toner image, and charging means provided with a magnetic particle layer contactable to said image bearing member to charge said image bearing member; and   determining means for determining when an image forming operation of said image forming means is to be prohibited, wherein the determinations are made in accordance with a density of toner returned from said charging means to said image bearing member.   
     
     
       52. An apparatus according to claim 51, wherein said image forming means includes developing means for developing with the toner a latent image formed on said image bearing member, and said developing means removes residual toner from the image bearing member simultaneously with its developing operation. 
     
     
       53. An apparatus according to claim 51, wherein said image bearing member has a surface layer having a volume resistivity of 1×10 10  -1×10 14  Ωcm. 
     
     
       54. An image forming apparatus comprising: image forming means for forming a toner image on a recording material, said image forming means including an image bearing member for bearing a toner image, charging means provided with a magnetic particle layer contactable to said image bearing member to charge said image bearing member, and transferring means for transferring the toner image from said image bearing member onto the recording material; and   determining means for determining when an image forming operation of said image forming means is to be prohibited, wherein the determinations are made in accordance with an amount of residual toner on said image bearing member after image transfer operation of said transferring means.   
     
     
       55. An apparatus according to claim 54, wherein said image forming means includes developing means for developing with the toner a latent image formed on said image bearing member, and said developing means removes residual toner from the image bearing member simultaneously with its developing operation. 
     
     
       56. An apparatus according to claim 54, wherein said image bearing member has a surface layer having a volume resistivity of 1×10 10  -1×10 14  Ωcm.